This is a very interesting question, Cathy, which has drawn me for a long time. Division is often conceived of as separation but it is also a meand of establishing a whole. Thus a quarter of 36 is 9, but 4 x 9 = 36. Durkheim in The Division of Labour in Society argued that the point of divided labour was not just efficiency (Adam Smith) but interdependence. The origin of the word distribution is indicative of all this. the Latins were a rabble who thought they needed more organization, so they split themeselves into three groups (tribus = tribe), held a ritual where they sacrficied a cow, divided the meat betwee the three and thereby consitutd themsalves as a stronger whole.
I always say that nationalism i slike racim but without the pretension to being so inclusive. nations are just identities opposed to the rest, but races are divisions of a whole set.
I am not sure that anthropologists have a lot to say about this issue, but this anthropologist certainly does. See for example my essay The globalization of apartheid. Keith